Search Results (3)

In this article, we present research results on the structure and properties of new self-lubricating antifriction composites based on 4H4VMFS tool steel grinding waste with solid lubricant additives. The new composites are designed to work in the friction units of offset cylinders in printing machines at rotation speeds up to 7000 rpm and increased loads up to 5.0 MPa. The developed technology formed composites with a fine-grained heterophase structure with a metal matrix base of tool steel 4H4VMFS regenerated grinding waste, consisting of high-alloy α−solid solution and hard grains of alloying element carbides, as well as evenly distributed CaF₂ antiseizure solid lubricant. This structure ensured the formation of composites with favorable functional properties. During the friction process, antiseizure films were formed on the contact surfaces, resulting in a self-lubrication mode. Comparative tests for friction and wear showed significant advantages of the new waste composite compared to cast bronze parts, which are traditionally used in the friction units of offset cylinders of rolled newspaper printing machines. The stable operation of the new composite made it possible to ensure a “wear-free” effect. Studies have shown the importance and prospects of using the wide range of valuable grinding waste in the reproduction cycle to manufacture quality composites. Reuse of such waste would significantly protect the environment from pollution connected with human activity industrial and mitigate negative impacts on ecosystems and the biosphere. Full article

Diamond-like carbon (DLC) films have attracted considerable interest for application as protective films in diverse industrial parts. This is attributed to their desirable characteristics, such as high hardness, low coefficient of friction, gas-barrier properties, and corrosion resistance. Antiseizure properties, in addition to wear resistance, are required during the die molding of polymer and polymer-matrix composite parts. Graphite films can be easily peeled because the vertically stacked graphene sheets are bonded via weak van der Waals forces. The present study demonstrates the fabrication of multilayered DLC/Cu films, where the Cu film functions as a catalyst for the formation of a graphite-like layer between the DLC and Cu films. The DLC/Cu film was synthesized on a Si (100) substrate via plasma-enhanced chemical vapor deposition and magnetron sputtering. The peelability, wear resistance, microstructure, texture, and cross-section of the film were experimentally analyzed. The results indicated a variation in the peelability with the deposition conditions of the Cu film that comprised particles with diameters of several nanometers. The DLC film at the interface in contact with the Cu film was transformed into a graphite-like state i.e., graphitized. The surface of the multilayered film exhibited antiseizure properties with the peeling of the upper DLC film. The multilayered film also exhibited wear resistance owing to the repeated appearances of a new DLC film. It is expected that the wear-resistant films with antiseizure properties demonstrated in the present study will be utilized in various industrial sectors. Full article

Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40–80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester) and characterized by scuffing load (P_t), seizure load (P_oz) and limiting pressure of seizure (p_oz). Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the P_t values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value. Full article